Project Summary ? Parent Award R00CA215307 Cancer cells have a distinct metabolism that supports their pathological proliferation. Targeting this metabolism has led to many of the existing chemotherapies in the clinic today such as antifolates. The amino acid glycine is primarily produced by folate metabolism, a pathway that is nearly universally upregulated in cancer. Glycine supports important biosynthetic processes including protein, purine and glutathione synthesis. In addition, glycine catabolic processes have recently been shown to be important in cancer stem cells and glioblastoma. In newly published data, I demonstrated that glycine-supported antioxidant production is crucial for cancer cell growth. This proposal seeks to quantitatively characterize glycine metabolism in cancer and to test the hypothesis that folate-mediated glycine synthesis supports glutathione production and thus redox homeostasis. In these efforts, I will benefit from a new small molecule that I discovered, which potently inhibits both isozymes of the glycine synthetic enzyme SHMT. In Aim 1, I will use isotope tracers to quantitate glycine production and consumption fluxes in normal and cancer cells, and apply these findings in vivo. I will further use these techniques to identify the membrane transporters that facilitate glycine entry into the cell. In Aim 2, I will test whether changing glycine availability in vivo affects tumor progression. I will do this pharmacologically with an optimized in vivo active SHMT inhibitor in models of hematological malignancy and through diet by modulating the amino acid content in food. Collectively, these experiments will lay the groundwork for targeting of glycine metabolism as a new therapeutic approach in cancer. Supported in my new tenure-track position at the University of Utah, this proposal will launch my independent research career.